The purpose of this research project is to further our knowledge of the basic phenomena of electrically augmenting bone healing. A well developed rabbit animal model is to be the basis for continuing research. Our previous research has shown the following points: within reasonable limits of power dissipation, or current density, waveform or frequency seem to have little effect upon optimization of the augmentation phenomena. Experiments with anodized tantalum electrodes have shown oxidation reduction reactions occurring at the electrode surface are of little importance to the augmenting phenomena. The augmentation process seems to be effective throughout the healing period, no triggering phenomenon is observed. Several areas concerning stimulation require further research for understanding and correct utilization. The variables responsible to best stimulate are not known. The variability between animals is not understood. Why is it more effective in certain animals? The biochemical alterations which occur in vivo need to be understood and investigated in the in vivo situation. The comparison between electrode stimulation and electromagnetic coils need to be performed within the same animal model so that a direct comparison between the two methods can be made. Further development of the promising phenomena of stimulating ingrowth into porous titanium and ceramic substrates needs to be continued. A standard protocol and animal model previously developed will be employed. Coils will be produced and positioned to externally stimulate the same osteotomy system used for implanted electrodes. Biochemical analysis involving hydroxy-proline, proline cyclic AMP, cyclic GMP, and calcium levels will be continued. Electro-developed to assist in explaining the behavior of bone ingrowth into pores during electrical stimulation.